Radio receiving apparatus



Nov. 2 1926. 1,605,627

R. E. THOMPSON RADIO RECEIVING APPARATUS Filed April 17, 1922 3 Sheets-Sheet 1 Nov. 2,1926. 1,605,627

R. E. THOMPSON RADI-O RECEIVING APPARATUS Filed April 17, 1922 3 Sheets-Sheet Nov. 2 1926.

EFF'ICIKNCY 1,605,627 R. E. THOMPSON RADI 0 RECEIVING APPARATUS File April 1'7, 1922 s Sheets-Sheet s IMPREssED FREQUENCY AND GRID CIRCUIT BROADLY *rumzo OI T WHERE RBSDNHNT ACTION IS MAx IMUM.

Waxiw: L ENGI" H InPREssEn FREQUENCY AND emu cmcun- BROADLY men.

PnNT WHERE Resounn-r Ae-noN :s Mnxumum.

vvnvs'. LsNe-r-H POINT WHERE NATURAL PERIOD OF GRID $IRCUTT-'CO'R'RB3 POND$ TO IMPRISSED FR Q E Y- WAVE: .LE.N-G"FH EFFECT OF NATURAL PERIOD 0F emu CIRCUIT DEST'ROVED DY INSCRTION 0F RISI8I'ANCI- wnu a L- EINGTH WORKING- RANGE; or UNTUNED s-Rm cmcurr b.

avwemto'c Patented Nov. 2, 1926.

- UNITED STATES PATENT OFFICE.

ROY- EDWIN THOMPSON, OF NYACK, NEW YORK, ASSIGN OR, BY MESNE ASSIGNMENTS, OF ONE-HALIEYTO 'WIRELESS IMPROVEMENT COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY, AND ONE-HALE TO WIRELESS IM- PROVEMENT COMPANY, INCORPORATED, 013 JERSEY CITY, NEWJERSEY, A COR- PORATION OF DELAWARE.

RADIO RECEIVIN 'APIARATUS.

Application filed April 17, 1922, Serial No. 554,127.,

My invention relates to improvements in radio receiving or amplifying systems, particularly such as are employed for amplifying currents of low intensity and high frequency in radio telegraphy or telephony, and particularly such as include electronic relays, detectors or amplifiers of the type comprising grid, filament and plate enclosed in a highly exhausted tube; and the same has for its object more particularly to provide a simple, efficient and practical system, which .may be readily adjusted by persons ordinarily unskilled in the adjustment of such apparatus. y p I v Further, said invention has for its object to provide a system of the character specified in which regenerativeamplification is accomplished over a range of frequencies without tuning adjustment in the grid circuit.

Further, said invention has for its object to provide 'a system of the character specified in which the grid circuit thereof has a rela 'tively high natural period to render the same substantially non-resonant and efli-' ciently operative over a range of frequencies to receive energy fromthe circuits associated therew th, and to permlt of regenerative amplification of said energy without necessi' tating the tuning of said grid circuit when it is desired to receive signals of another frequency. v

Further, said invention has for its object to provide a system of the character specified in which the grid circuit thereof has a relatively high natural period to permit ofthe same receiving from its associated circuits energy of different frequencleswithout tuning adjustment, and in which dampingmeans is disposed in said grid circuit to prevent resonant action the'r'e'in at the natural frequency thereof.

Further, said invention has for its object to provide a system of the characterspecified in which the plate circuit of the tube thereof tends'to feed back energy to the grid circuit, and in which damping means is disposed in said grid circuit to prevent resonant action at the natural frequency thereof and to prevent said tube from oscillatingduring the "amplification of the useful oscillations.

Other objects will in part be obvious and in part be pointed out hereinafter.

To the attainment of the aforesaid objects and ends my invention consists in the novel details of, construction, and in the combination,.connection and arrangement of parts hereinafter more fully described. and then pointed out in the claims. j ,Heretofore, all au dion receiving systems,

including regenerative or feed-back systems,

have depended upon resonance of. tuning efiects between the gridcircuit, that is to say the circuit connected to the grid and fila- The present invention embodies means discovered by me whereby the resonant grid circuit is replaced by anon-resonant grid circuit, so constructed and arranged that greater efliciency and simplicity of operation result, part cularly when the apparatus is operated by persons not highly skilled in resonant circuit. This circuit was either the resonant antenna circuit itself or a separate circuit associated therewith and made substantially resonant thereto. In all cases, the degree of efliciency of such circuits depended upon how near to the resonance point they were operated. While there were so-called untuned detector circuits, such circuits were 'untuned only inthe sense that exact tuning means were not provided, so-called broad-tuning being depended upon to impart a sufficient degree of resonance to the circuit as to make it operative-over aismall frequency range on either side of the point where it would be considered tuned. Generally speaking, the exact resonant point of such detector circuits is designed to lie about in the. middle of the range of frequencies rough adjustment or\step by step arrangement,and the frequency impressedther'eon.

ment is provided by which the resonant point of the detector. circuit can be roughly shifted to the general proximit of the resonant point of the associated clrcuit.

My present invention involves ne1ther a resonant nor a broadly tuned grid circuit. With the employment of my method, if the grid circuit'is given a natural period within the range of the associated tuned circuit, the reaction of grid circuit upon the tuned circuit will, at that point, greatly detract from the selectivity and efiiciency of the system as a whole unless additional means, as described herein, are utilized to prevent such reaction. This is probably due to thefact that such a close coupling '(i. e., intimacy of relation), between the non-resonant grid circuit and the associated resonant circuit, will incidentally destroy the efliciency of the system, should the grld circuit, under thisIcondition, be made resonant 'to the assoclated circuit. I, therefore, preferably give to the grid circuit such constants as to make its. 'natural or inherent wave length he wholly without and below the range of wave lengths which its associated resonant circuit is designed to cover. If, for the purposes of maintaining sufficient close coupling with the associated resonant circuit at the longer. wave lengths, it is found necessary to construct the-grid coil with so large a number of turns of wire as will incidentally result in an inherent natural fixed wave length which falls within the range of wave lengths for which the associated tuned circuit is designed -to be adjusted, then the grid; 0011 should be wound with resistance wire of such high resistance as to prevent it from reacting on-the associated circuit, should theassociated' circuit be adjusted to this polnt. In any case, the distributed capacity of the grid coil should be eliminated as nearly as possible and the number of turns of wire kept down, so that the inherent wave length of the coil will be as short as possible and still permit necessary coupling with the associated circuit. Should the grid circuit have an inherent wave length within the ran e of the associatedcircuit, the reaction at t is wave length, due to the close coupling which is necessary, will destroy the efliciency at and near that wave length. The windingof the gridcoil with resistance wire, as. above stated, prevents this reaction by preventing frequencies corresponding to the natural period of the coil from being set up. This reslstance is found useful for other purposes, in that it acts as a ballast to steady the operation of the audion and enables a greater strai ht detector amplification to be obtaine before the audion passes over into the oscillating state.

In the accompanying drawings, forming part of this specification, I have shown several circuits suitable for carrying my invention into effect. I do not wish to be understood, however, as limiting myself to the same, as various changes may be made therein Within the meaning of the present invention.

Referring now to the drawings Figure 1 illustrates diagrammatically, the circuit arrangement, in a simple form, where the capacity of the connections to the indicator T is utilized to by-pass wing pulsa: tions;

Fig. 2 shows substantially the same circuit but with a grid leak Y and condenser C inserted in series with the grid and with a bypass condenser C bridging the battery of the wing circuit and indicating device T;

, Fig. 3 is a sectional view showing the construction and association of antenna, wing and grid coils for a receiver having an antenna wave length range of from approximately 150 to 750 meters;

Fig. 4: is an end view of this coil construction;

Fig. 5 shows the windings and association of coils for. receiving waves over a range of approximately 300 to 3000 meters; and

Fig. 6 illustrates graphically the difference in the effect of an impressed frequency which corresponds to the period of (a) a resonant grid circuit, (6) a so-called untuiied detector circuit, and (a) my nonresonant grid circuit.

In practice, the efliciency peak of the curve diagram at, is maintained by tuning means to correspond with the impressed frequency. The peak of curve diagram 6, is always in fairly close proximity to the impressedfrequency, but in diagram 0, representing my apparatus, the efiiciency curve is the reverse of curves a and b and therefore resonance phenomena cannot be utilized and should be avoided.

The curve in diagram d, shows the result of destroying the effects of the natural period of the circuit where this period lies Within the range of frequencies to be received, which result is obtained by winding I the grid coil with wire having sufficient high resistance to destroy this detrimental effect. This curve is substantially flat, being efficient at all frequencies.

lVith reference now to the circuitsof Fig. 1: There is first, the antenna or frequency determining circuit, including the coil A, capacity C and ground. Second, the wing circuit, beginning at the wing W, through coil B, battery B?, indicating device T and filament F, back to the wing IV. Third, the grid circuit, starting with the grid G, coil R and filament F, back to the grid G. In circuit with the filament 'there is shown the usualbattery B and rheostat X. In the coupling shown, the intimacy of relation between. the antenna coil -A and the wing coil B, should be variable, especially if this wing shown in Figures 3, 4. and 5, or to other suitable methods of arranging the coils to secure this close coupling, as will suggest themselves to those skilled in ,the art, once the use and 'value of such close coupling be recognized.

Unless the coupling between grid circuit. and antenna be sufficiently close to transfer the antenna energy without the necessity of resorting to the gradual building up of the potential across the grid coil by meahs of resonant accumulation, then the antenna energy will not be efficiently transferred and the desired result will not be obtained. Also with this close coupling, the distributed capacity, inherent in all coils, together with the capacity of the connections, etc., must be reduced to a minimum. \Vhile this capacity is useful in resonant circuits, for obtaining resonance without the use of a parallel condenser, it is destructive of effi ciency in my non-resonant circuit and is to be eliminated as nearly as possible first, by

using as few turns of wire as may be found necessary, while retaining a sufficiently close coupling, second, by spacing these few turns as wide apart as possible, at the same time keeping them in the maximum magnetic field set up-by the antenna coil, and third,

by avoiding multi-layer winding, unless these layers are widely separated. These are, in general, the most effective rules to be i followed.

.Associated with an antenna circuit designed to cover a wave length range of 150 to 750 meters, I prefer to use a grid circuit, whose inherent wave length is no greater than 60 meters. That is, the shortest wave to be received is two and one-half times the fixe'd'inherent wave length of the grid circuit, or in terms of frequency the fixed natural frequency characteristic of the detector circuit is two and one-half times as high as the highest frequency to which the antenna is to be tuned.

The construction of the required apparatus for such a range is shown in Figs. 3

incl ded in the circuit for wave lengths from 150 to 400 meters and'all included for wave lengths from 400 to 7 50 meters; This coil is revolvable inside another tube,'hav- 111g an outside diameter of five and onecighth inches and a wall, one-sixteenth of an inch thick, upon which is wound the .antenna coil A, in four layers of twelve turns per layer, each layer being tapped. Around the outsideof the outer layer of this coil A, I place two layers of paper one one-hundredth of an inch thick and over this paper wind, in a singlelayer, ten

turns of No. 40 B & S wire, five turns on each side of the five-sixteenths inch vacant space'in the center. The turns should be spaced approximately one-sixteenth of an inch apart, so as to cover the same overall space as is covered by the coil A winding,

and also to reduce distributed capacity to a minimum. 'Preferabl'y, the fine wire for thisgrid coil should be of high specific'resistance, such as Advance, nichrome or other well known high resistance alloy. Although desirable, resistance wire is not essential and copper or other wire may be used.

Fig. 5 shows the construction of coils for the antenna circuit, having a wave length range of from 300 to 3000 meters. The inherent wave length of the grid circuit here is approximately 150 meters, this being due to the additional turns necessary for coupling close enough to the antenna circuit when the latter circuit is adjusted for the longer wave lengths. Here the plate coil B is wound with one hundred and twenty turns of 20/38 Litz wire, on a cylindricaltube one and one half inches long and of an outside diameter of four'inches. This coil is slidably arranged to move into and out of the cylinder upon which is Wound the coil A, which cylinder has an inside diameter of four and seven eighths inches and an outside diameter of the inches andupon which is wound the antenna inductance in fourlayers of forty turns each, tapped at each layer. Over the outside layer of coil A'is slipped a thin tube upon which is wound grid coil R, consisting of one layer of fine wire such as f0. 40 B and.

S gauge Advance wire or copper magnet wire, spaced approximately one thirty-see 0nd of an inch apart.

The capacity used with the coil A, for accurate tuning, may be in series for the shorter Waves and in parallel for the longer waves.

Having, therefore, described my invention, .I cla1m 1. An amplifying system comprising a frequency determining circuit, adjustable over a range of frequencies, an electronic tube including grid, filament and plate, a grid circuit for said tube coupled with said frequency determining circuit to receive energy therefrom, and a plate circuit for said tube arranged to feed back energy into said grid circuit; said grid circuit having anatural frequency fixed outside of the working range 'of said frequency determining circuit, whereby to render said grid circuit substantially non-resonant at the frequencies Within the working range of said frequency determinin circuit, and operative to receive energy tilierefrom'and from said plate circuit over said frequency range under the nonresonant conditions existing in said grid circuit.

2. An amplifying system comprising a frequency determining circuit adjustable over a range of frequencies, an electronic tube including grid, filament and plate, a secondary circuit connected to said tube to form a grid circuit, and coupled with said frequency determining circuit to receive energy therefrom, and a plate circuit arranged to feed back energy into said grid circuit; said grid circuit having electrical characteristicsof values fixed to render the same pen manently non-resonant at said frequencies with a natural frequency-fixed adjacent to the upper end of said frequency range, and operative to receive energy from said frequency determining circuit and said plate circuit over said frequency range under the non-resonant conditions existing in said grid circuit. 1

3. An amplifying system comprising a frequency determining circuit adjustable over a range of frequencies, an electronic tube including grid, filament and plate, a grid circuit coupled to said frequency determining circuit to receive energy therefrom throughout said frequency range, damping means in said grid circuit disposed in series with the grid and filament of said tube and serving to prevent resonant action 1 in said grid circuit at the natural frequency thereof and to prevent saidrtube from oscillating during the amplification of the use ful oscillations, and a plate circuit tending to feed back energy to said grid circuit.

4. An amplifying system comprising a frequency determining circuit having a defi-. nite frequency range, an electronic tube in cluding grid, filament and plate, a non-resonant grid circuit coupled to said frequency determining circuit to be excited thereby efficiently over said range of frequencies and having a natural frequency adjacent to the upper end of said frequency range of said frequency determining circuit, means in cluded in said grid circuit to prevent resonant action therein due to the natural frequency thereof, and a plate circuit arranged to feed back energy into said gridcircuit.

.5. An amplifying system comprising a frequency determining circuit of definite frequency range, an electronic tube including grid, filament and plate, and a non-resonant grid circuit coupled to said frequency determining circuit to be excited thereby over said range of frequencies, the secondary of said coupling including a coil of high resistance wire in said grid circuit.

'6. An amplifying system comprising a frequency determining circuit having a definite frequency range, an electronic tube including grid, filament and plate, a nonresonantv grid circuit coupled to said frequency determining circuit to be excited, thereby over said frequency range and having a natural frequency adjacent to the upper end of said frequency range, said coupling including a secondary coil of high resistance wire in said grid circuit for preventing resonant action therein due to said natural frequency.

' 7.1An amplifying system comprising an aerial receiving circuit, adjustable means for rendering said circuit resonant over a range of frequencies, an electronic tube including grid, filament and plate, a non-resonant grid circuit coupled to said aerial circuit to be excited thereby over said range of frequencies and having a natural fre-.

quency adjacent to the upper end of said range of frequencies, means therein for damping theeffect of the natural period thereof, a plate circuit, means for transfer ring therefrom back to said grid circuit energy corresponding in frequency to the frequency for which said aerial circuit is adjusted, and indicating means associated with said plate circuit.

ROY EDWIN THOMPSON. 

